But with temperatures today and tomorrow nudging 16C comes a warning that snow could mark the first official day of spring on Tuesday.

A Met Office spokesman said: "Enjoy the warm weather while you can because you will have to wrap up soon."

Wildlife experts said animals such as moles, bats and hedgehogs that woke early from hibernation could be at risk of starvation because of the snow.

The Met Office said the cold snap will hit the North first and filter down to London by late on Sunday. Temperatures will plunge to minus 4C.

Arctic winds are predicted to sweep the country, bringing snow, hail, frost and ice. It is expected to begin to ease off by Wednesday.

Despite the blast of cold, weather experts predict this could be the hottest year on record.

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Scientists said El Niño, rather than global warming, was the most likely cause. The National Oceanic and Atmospheric Administration in the U.S. said the weather phenomenon, a seasonal warming of parts of the Pacific Ocean, was helping to create the warmth - not greenhouse gases.

Woolworth's, the UK's biggest retailer of ice creams, said the warmer weather had "changed the way we buy and stock ice creams by bringing the whole process-forward".

Adam Hill, ice cream buyer for the chain's 900 stores, said: "We're no experts in the effects of global warming, but we are seeing customer demand for ice creams much earlier than three or four years ago.

"People have been going to the seaside and parks and spending time in the garden in the past couple of weeks and that creates demand for ice creams and other outdoor living products."